1. Field of the Invention
The present invention relates to a pipe produced by shaping a plate material to be cylindrical and joining one- and the other-side edge portions to each other, and a method for producing such a pipe.
2. Description of the Prior Art
Recently, in a heat exchanger for a condenser or the like, a tank body is made of an aluminum pipe member 13 as shown in FIG. 19.
Conventionally, such a pipe member is produced by shaping a plate member 11 into cylindrical and brazing a one-side edge portion 11a and the other-side edge portion 11b to each other as indicated by R in FIG. 16.
However, if such a conventional pipe member 13 is heated to a high temperature in a brazing furnace for brazing, the one-side edge portion 11a and the other-side edge portion 11b of respective half cylindrical portions of the pipe member 13 separate from each other with a point A as a hinge as shown in FIG. 17 since the strain occurred by press molding is released in the pipe member 13, so that it becomes difficult to braze the one-side edge portion 11a and the other-side edge portion 11b to each other surely.
Conventionally, therefore, the one-side edge portion 11a and the other-side edge portion 11b of the pipe member 13 are subjected to spot welding W at points at intervals in advance as shown in FIG. 18, before the one-side edge portion 11a and the other-side edge portion 11b are brazed to each other.
However, there has been a problem with such a conventional producing method that a large number of steps are required in producing the pipe member 13 since the one-side edge portion 11a and the other-side edge portion 11b of the pipe member 13 are necessary to subjected to spot welding W at points at intervals in advance.